Endurance is essential for any runner and is probably the most variable if you want to run well in races. As track season or the Summer falls into Autumn, speedwork is no longer the focus as our attention turns to the base phase of our training – building endurance.

The base phase of training usually lasts between 12 – 16 weeks although this can be stretched to 24 weeks. The base phase aims to develop our aerobic base. This is also known as endurance and is what allows us to run for such a long time in the aerobic zone where we are not producing lactate which will quickly bring our running efforts to a stop as our body fails to clear the lactate from our blood. In the base phase we want to increase the speed we can run at whilst still working aerobically for instance, when you start you can run 13 kph aerobically, but when you finish you may be able to run 14 – 15 kph aerobically.

Although this may only seem so important for 5k runners and above, this is not the case as the aerobic system produces most of the energy required in distances as short as the 400m sprint!

In fact, according to U.K. Athletics coach, Brian Mackenzie, the 400m sprint is actually 62% aerobic and 38% anaerobic. Wow! So for running 400m, you are still primarily using your aerobic system which runners in the marathon utilise so dominantly over the anaerobic system (about 97.5% aerobic and 2.5% anaerobic).

Base Phase Training – What is my Aerobic Pace?

MAF Method

Ensure that you are running the vast majority of your miles at an aerobic pace. One way I like to use to calculate your max aerobic heart rate is the MAF method. To use this method you need to:

  1. Subtract your age from 180
  2. Modify this number by selecting among the following categories the one that best matches your health and fitness profile:

a)  If you have or are recovering from a major illness (heart disease, any operation or hospital stay, etc.) or are on any regular medication, subtract an additional 10.

b)  If you are injured, have regressed in training or competition, get more than two colds or bouts of flu per year, have allergies or asthma, or if you have been inconsistent or are just getting back into training, subtract an additional 5.

c)  If you have been training consistently (at least four times weekly) for up to two years without any of the problems in (a) and (b), keep the number (180–age) the same.

d)  If you have been training for more than two years without any of the problems in (a) and (b), and have made progress in competition without injury, add 5.

This gives you a rough indicator as to what your maximum aerobic heart rate is. During easy and steady state runs, aim if possible not to exceed this number. The pace may feel very slow, but stick with it for 4 – 8 weeks and see how your pace increases overtime whilst maintaining the same heart rate. There is even a test, known as the MAF test to demonstrate how you should improve.

70 – 80% Max Heart Rate

Another way of determining your aerobic zone is to:

  1. Subtract your age from 220
  2. Multiply that number by 0.8

That will give you another number for what your maximum heart rate should be during your easy and steady state runs.

Rate of Perceived Effort (RPE)

For those of you who don’t use heart rate monitors or have access to them, another way of determining your aerobic zone relies on how you feel. From a scale of 1 – 10, your maximum rate of perceived effort during the base phase should be between 4 and 7.

Base Phase Training – The Main Components

During the base phase, you should aim to increase your total mileage – that should be your main focus. You can do this in 3 ways:

  • Gradually increasing mileage
  • Add a longer run into your training plan
  • Include 1 faster paced runs each week

Make sure your increase in mileage is gradual so you can increase strength, running economy and injury resistance. Don’t rush to build your mileage up otherwise you’ll be more prone to injury as you won’t be giving your body sufficient time to adapt to the training.

It is important to note that most of these runs should be performed at steady state or easy pace due to the high volume of training you will be placing upon your body. Steady state is a pace which doesn’t feel ‘easy’ or ‘hard’. Note that this is not tempo pace. If you are running in steady state you will have the ability to freely slow down or speed up if you wish. It tends to be around 70 – 85% max heart rate.

Base Phase Training – Increasing Mileage

  • Add double day easy runs or extra runs into your weekly schedule (get that morning run in even)
  • Increase easy run mileage by 1 – 2 miles every couple of weeks
  • Increase the duration of your long runs by 1 – 2 miles every couple of weeks

Base Phase Training – Run Long

Along with covering more miles, running for longer distances at an easy or steady state pace will have the following benefits:

  • Denser mitochondria (the cell organelle where energy is released)
  • Increased cardiac output
  • Increased oxygen uptake
  • Increased lung capacity
  • Enhanced running economy (higher running efficiency)
  • Denser capillary networks (increases oxygen delivery to muscles)
  • Increased muscular strength and endurance (from pounding the ground more than usual!)
  • Mental toughness (especially if running alone)
  • Increased number of aerobic enzymes (to produce ATP to use to release energy)

If you can get your training right in the base phase, the muscular strength you will have gained will also help to make you a more injury resistant runner. No matter what distance you run, you should aim to try and get a long run in on a regular basis whether that’s every week or every 3 weeks.

Base Phase Training – Faster Paced Runs

Whilst it can be easy to fall into the routine of doing lots of slow easy miles, you want to try and include some shorter, faster paced runs in order to maintain leg efficiency, running economy and neuromuscular fitness (so your brain can send signals for your muscles to contract quickly and efficiently).

As well as adding shorter hill sprints and strides into your training, you can add faster paced runs like:

  • Tempo runs (keep them short though in the base phase – I’d recommend less than 15 minutes)
  • Progression runs (where you gradually dial the speed down to lactate threshold or just below – these runs can last a varying amount of time depending on how fast you are going and when you decide to increase the pace)
  • Fartleks (easy running mixed with hard efforts e.g. running 6 minutes easy pace with 2 minutes fast – don’t do these too often yet as they can be a bit more taxing, so I’d suggest maybe do every couple of weeks at most)

These runs will help to keep your neuromuscular fitness in shape although it may not develop much (that will come during the speedwork)!

What is your plan for your base phase of training? Let me know down below!